1. Field of the Invention
The present invention relates to a layer editing method and apparatus in a pen computing system.
2. Description of the Related Art
Computers, PDAs, mobile terminals, and similar devices are generally configured to enable a user to input text, data, or computer commands using a physical keypad. Recently, touch screen panels (TSP) have been adopted for use with such devices, in order to provide an alternative method of inputting information. When compared to information input by a keypad, information input by a touch screen panel is convenient and greatly enhances the user's experience. In addition, touch screen panels may be used to efficiently input information into small information processing terminals such as PDAs and mobile terminals where a key input device is not practical.
Conventional input devices having a touch screen panel detect a trail left on the touch screen panel by a writing instrument such as a stylus. The device recognizes a character or a symbol corresponding to the trail and converts the recognized character or symbol into a predetermined computer code
A method of editing text by writing is described in U.S. Pat. No. 5,297,216 issued to Sklarew. According to this patent, when an insert symbol is written on a screen displaying original text, a popup window for insertion is created so that the user can write characters or symbols in the window.
According to U.S. Pat. No. 5,297,216, if the user writes an editing symbol on a screen displaying original text, an editing apparatus recognizes the symbol and pops-up a separate window for insertion over the original text. The user can then write additional characters and symbols in that window. The editing apparatus recognizes the handwritten characters or symbols and then translates them into font symbols. The editing apparatus allows the user to confirm the font symbols. Upon confirmation by the user, the editing apparatus inserts the font symbols into the original text. U.S. Pat. No. 5,666,139, issued to Thielens, provides for a popup window for editing text, wherein the pop-up window takes the form of a writing pad.
In the prior art editing apparatus described above, it is time consuming to request and display a popup window for editing text. Also, it is inconvenient for a user to write characters or symbols within the limited area of the pop-up window. It is a further disadvantage that the editing apparatus fails to recognize characters or symbols entered outside of the window. In addition, the conventional editing apparatus, as described above, only stores text in a final edited form. Thus, where text was edited several times, a user cannot confirm which changes were made to the text at each editing step.